Fluid pressure hammer



Oct. 17, 1933. E. w. STEVENS 1,931,042

FLUID PRESSURE HAMMER Filed Jan. 12, 1931 2 Sheets-Sheet 1 l2 7 ilk K 7 ig- INVEN fon ara W. fi'zeye A TTORNEY.

Oct. 17, 1933. w. STEVENS 1,931,042

FLUID PRESSURE HAMMER Filed Jan. 12, 1931 2 Sheets-Sheet 2 6; W ////7///////// 22" I k u ah Q RIQ'QQ xxx,

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enema oct. 11, 1933 1,931,042 I F UID PRESSURE HAMMER Edward W. Stevens, Detroit, Mich., assignor to Chicago Pneumatic'Tool Company, New York, N. Y., a corporationof New Jersey Application January 12, 1931. Serial No. 508,126

' 8 Claims. (o1.121 19) This invention relates in general to tools of the percussive type actuated by fluid pressure ports in alternation with its inner face.

After much experimentation the discovery has been made that the edges of the ring valve need not be closely confined by walls. with which the valve edges have sliding contact, as disclosed in my copending application, .but that improved operation and a much simplified construction may be secured by mounting the valve in. a recess with-ample clearance in a directiontransverse to the direction of movement of the valve.

The valve is then automatically centered in the recess by the pressure fluid which passes over both edges, thereby producing a floating eifect upon the valve and practically eliminating frictional resistance to its movement. I

Among the objects of the invention are to provide an improved arrangement in which live pressure fluid will pass simultaneously over both edges of a valve of the described type and produce a floating or balancing efiect upon the valve, to reduce friction and wear upon-the valve, to simplify the construction andto lower manufacturing costs, and in general to improve prior devices both in structure and in functional operation. I I V In order to illustrate the invention concrete embodiments thereof are shown in the accompanying drawings, inwhich: 1 Fig.1 is a longitudinal sectional view of a small hand hammer showing a portion of -the handle in elevation; e

Fig. 2 is an enlarged detail, sectional view of the hammer shown in Fig. 1 with; certainunestially on the line 33 of Fig. 2;

Fig. 4 is a longitudinal sectional view illustrat ing the invention. as applied to 'a percussive drill of the axis of the cylinder to seatupon and seal which limit the valve recess.

sential elements omitted and with the valve having rotation mechanism, forv the drill.'steel;

Fig. 5. is.an enlarged detail sectional view showing bothpiston and valve in different position from that shown in Fig. 4; and

Fig. 6 is a transverse sectional view substane tially on the line fi6 of Fig. 5. V

Figs. 1.to 3 inclusive, disclose the invention in its essentials only and in a commercially developed toolof the small hand type commonly referred to as a chipping hammer. prises merely four parts, a cylinder? providing a piston chamber within which reciprocates a piston 8, the operationof which is controlled by a valve 9, the chamber for which is provided by. a closure member 10 secured to cylinder 7 as by a threaded connection. Cylinder '7' has passages 11, two in number (Fig. 3), leading to the forward end of the piston chamber and short passages 12 leading to the rear end of the piston chamber both under control of valve 9 as will be presently described. Cylinder '7 also has ,exhaust ports 13 and 14 through the wall thereof 1on trolledsolely by piston 8. Valve Sis a narrow tubular, annular or ring member which tele-, scopingly engages, a reducedportion 7a of cylinder 7 and is retained in place by closure member 10. Portion 7a is further reduced, eccentrically, atleast on one side to provide opposedseats 15 and 16, the, former having ports 11;; connecting with passages 11 while passages 12 extend directly through reduced portion 'Za'of the cy1in-. der and seat 16. Hence ports 11a and passages 12 are controlled by the inner face of 'valve 9,

As clearlyshown in Figs. 1 and 2 the recess defined by the reduced portion 7a of cylinder 7 and:by closure member 10 and in which valve 9, ismounted, is ofexcess width inrelation to the, length of the valve.. In operation valve 9 maintains; a central position withinrthe, recess, the pressure fluid, which may be admitted into the .valve chamber by passage 17 extending through thegrip portion of closure member 10, flows, simultaneously and equally over and aroundboth edges or ends of theValve maintaining the latter in a partially balanced condition and keeping it out of contact with the walls Hence the valve is quite free. ofany frictional resistance to its. movement. To" 'give the pressure. fluid, easy access to the inner face of the valve both edges or ends may be bevelled inwardly. as indicated at9a. in Figs. 1 and2. Since the cycle of opera.- tion of tools having. a piston-controlled. exhaust and. an automatically thrown. valve controlling the admission of pressure fluid only .well known to those skilled in. the art,-descrip,tion

It com- 7 above tool are apparent. are required in the cylinder and the seats for 'the valve on the reduced portion 7a areconveniently made since they are on the exterior of the cylinder. An added economy is that identically the same Valve may be used forhammers of different length of stroke, the only require-- ment for maximum efficiency being that the. throw of the valve, transverse to the axis of the cylinder, be sufiicient to admit the additional quantity of pressure fluid required for the additional length of stroke. This is easily accomplished when valve seats 15 and 16 are ground by changing the eccentricity of one of the seats. Inasmuch as thepressure fluid is arranged to pass freely over both edges of the valve only a very small movement of the latter is required.

, For example, in the form of the invention shown inFigs. 1, 2 and 3 a hammer with a' cylinder providing a pistonstroke of 1 /2" has a valve movement of only .015, a 2 stroke hammer requires valve movement of only .020, and a 3. stroke hammer valve movement of .031. The small movement of the valve with the floating effect due to the pressure fluid passing freely vover'the edges of the same from the body of.

pressure -.fluid surrounding the exterior of the valve insures quick action and an almost totalv absence of wear. Moreover, economy in equipment results from the factthat the same handle and valve may be used on cylinders of different stroke for thehammer piston.

Figs. 4 to 6 inclusive disclose the application of the invention to a different type of fluid pres-' sure percussive tool, namely a percussive drill having automatic means for rotating'the drill steel. The drill comprises a cylinder 20 within which reciprocates a hammer piston 21 controlling main exhaust ports 22 and 23 and adapted torimpart blows directly to a drill steel 2 a 24 supported in a rotary chuck 25 mounted in a front head'26 secured to cylinder 20." The opposite end of the cylinder is closed by a member or support 27 having a reduced portion 270; which together With cylinder ring 28' provides a recess for the'narrow tubular, annular, or ring valve 29 conforming to-valve 9 of the first described modification. Beyond cylinder ring 28 is disposed a ratchetring 30 and inwardly of the'same and cooperating therewith is rifle bar 31, the splined extension of which projects through and has a bearing in ring 28 and closure 27 and extends into the piston chamber to'co-' connection and thence to steel. 24 in a wellknown manner. y I V The reduced portion of support 27 is ground to provide opposed seats 35, 36 conforming to seats 15 and 16 of the first-described form of the invention, to be engaged by the innerface of valve'29. Ports in seat lead into a pasjsage 37 having return bends connecting with a passage. 38 in cylinder 20 leading to the front end' of the. piston'chamber. Ports in seat 36 open into'a passage 39 extendinginto the rear end of the piston chamber. Pressure fluid, admitted by a supply conduit (not shown) connected to threaded opening 40 in cylinder 20, has identically the same action upon valve 29 as in the first-described modification, the valve being sub stantially balanced and floated by the simultaneous and equal passage of the fluid over and around both edges thereby centering the valve in the recess and keeping it out of contact with the limiting Walls of the same. Both edges of the valve are bevelledtoward the inner face as indicated at 2911.

In a drill of the type shown in Figs. 4 to 6 inclusive, it is frequently necessary to blow the hole, in, order to remove accumulated cuttings and to prevent the same from jamming the drill steel so that it cannot be rotated by the drill mechanism. For this purpose aplun'ger. 41 is arranged to be projected through the cylinder wall to engage valve 29 and hold it against seat 36 so that the pressure fluid will continue to pass through passages 37 and 38 to the forward end of the piston chamber whence it passes along the splines to the piston extension' and rotary chuck 25 into the bore of the $3 hollow drill steel 24. .Plunger 41 has aflange 42 yieldingly maintained in engagement Wlth closure 43 through the action of coil spring 44. Plunger 41 also has an extension beyond flange 42'terminating in a head 45 adapted to be pressed by the thumb or finger of the operator. By preference closure 43 has an annular flange 43a enclosing plunger head 45 to prevent accidental operation of the latter.

While the invention has been herein disclosed in What are now considered to be preferred cylinder, a piston .reciprocable therein, means providing an annular valve chamber having opposed arcuate seats on the inner wall thereof and ports and passages extending from said seats to the opposite ends of the piston chamher, and an annular valve of less length than said chamber for engaging said seats with its inner face in alternation.

2. A fluid pressure percussive-tool having a cylinder, a piston reciprocable "therein, means providing an annular valve chamber disposed transversely to the axis of said cylinder and having opposed arcuate seats on the. inner wall thereof with ports extending from said seats respectively to oneor the other end of the piston chamber, means supplying pressure fluid tosaid trally of said chamber bythe pressurefluid passing over both edges of said valve to reach a said ports.

3. In a fluid pressure operated percussive tool,

the combination of a ring valve and a support teles'copingly engaged by the same, said support being somewhat reduced to provide seats engaged by the inner face of said valve in alter i.

nation and ports in said seats for control by saidvalve, said support providing clearanc'efor said valve permitting movement of the latter in two directions angular of eachotherJ J 4. In afluid pressure operated percussive tool,

' the combination of a ring valve and a support telescopingly engaged by the same, said support being somewhat reduced to provide seats engaged by the inner face of said valve in alternation and ports in said seats for control by said valve, said support providing clearance for said valve permitting movement of the latter both axially and laterally of said support.

5. In a fluid pressure operated percussive tool, the combination of a narrow tubular valve, a support having a reduced portion telescopingly engaged by said valve, said reduced portion being still further reduced eccentrically to provide opposed seats engaged by the inner face of said valve in alternation and ports in said seats under control of said valve, and a member abutting said support to define the valve recess provided by said reduced. portion of said support, said recess exceeding the length of said valve to permit the pressure fluid to pass over both edges or ends of the same and to keep said edges out of contact with the parts of said support'and member which limit said recess.

6. In a fluid pressure operated percussive tool, the combination of a narrow tubular valve, a support having a reduced portion telescopingly engaged by said valve, said reduced portion being still further reduced eccentrically to provide opposed seats engaged by the inner face of said valve in alternation and ports in said seats under control of said valve, and a member abutting the reduced end of said support to define a valve recess in excess of the length of said valve, both edges of said valve being bevelled inwardly towards its inner face to give the pressure fluid convenient access to said last-named latter for engaging said seats in alternation with its inner face, and meansadmitting pressure fluid within said closure about said reduced portion of said cylinder.

8. A fluid pressure tool having a cylinder, 2. piston reciprocable therein, said tool providing substantially concentric walls and limiting end walls forming an annular valve chamber, a ring valve in said chamber of such size relative thereto that said valve contacts only said inner, wall of said chamber and only with opposed portions of its interior surface in alternation, and means supplying pressure fluid to. said chamber, the

inner wall of said chamber having ports communicating with opposite ends of said cylinder for control by said valve.

EDWARD W. STEVENS. 

